"Jim Carr" wrote in message
news:s_49d.334$_a3.3@fed1read05...
"ZZBunker" wrote in message
om...

I am snipping your explanation not out of disprespect but simply because I
don't understand a lot of it and I think it exceeds the discussion.

Porky wrote, "the source's motion causes the apparent wavelength of the
sound to shorten." I disagreed. I will try to state my disagreement more
simply: The apparent *frequency* shifts. However, the wavelength either
shifts or it doesn't depending on whether the source if moving.

Suppose I have a machine that sends a ball rolling in a straight line at
10
feet per second. I launch one ball per second. I think we would agree that
the balls are 10 feet apart. Now, if I move my machine at 5 feet per
second
in the same direction as the balls, then each ball will be five feet
apart.
That's the wavelength.

That isn't a good analogy, if the machine is launching balls at ten feet per
second and you start moving it forward at 5 feet per second, the balls are
now being launched at 15 feet per second. The train whistle is "launching"
sound waves at approximately 1140 feet per second, regardless of the
velocity of the train. The distance between the balls has no relevance to a
sound's wavelength.

Frequency is a different matter. If there is a wall some distance away,
the
balls launched from the stationary machine will hit the wall a frequency
of
one per second. In the second case the balls will strike the wall at one
per
half second until eventually my machine crashes into the wall and I lose
my
government grant.

With sound, or anything else that travels in "waves", the relationship of
wavelength to frequency is fixed, if you change one, you change the other.
Look at the equations, if "F" = frequency, "W" = wavelength, and "C" = the
speed that waves travel in the medium, then F=C/W, and W=C/F. The
relationship is absolute, that's why your machine/ball analogy doesn't
apply.

If in the first scenario I move the wall at 2 feet per second towards the
oncoming balls, the balls will strike the wall at a frequency of one every
0.8 seconds. I still say the balls are 10 feet apart. The frequency
changed
because the wall was moving, but distance between the balls didn't change.

If the balls traveled down a lane that had a line painted once per foot,
and
I took a snapshot of the balls, I could clearly see that they were 10 feet
apart.

I think that to describe Doppler shift accurately one should state that
the
apparent frequency shifts in all cases but that the wavelength only
changes
if the source is moving. Our ears only measure frequency so the net effect
is the same.

Would you agree or disagree with this explanation?

Disagree for the reasons I listed above, you can't change frequency
without changing wavelength.

"Bob Cain" wrote in message
...


Porky wrote:

I don't think so, I'm not arguing that the distortion you're defining
doesn't exist, I'm saying it's the result of a phenomonen other than
Doppler
shift.

It is the only distortion phenomenon that follows from the
motion of the source, so call it what you wish. That its
magnitude is a minimum, zero, when the velocity due to the
LF is a maximum just belies the usual picture people have of
what is going on and the way it is often described.

An elephant fart may exceed 90 dB SPL at ten feet, and the elephant's
anus is smaller in diameter than an eight inch woofer. You'll have to
measure excursion, I ain't gonna get close enough.:-)

There's a very signifigant excursion there if you consider
its equivalent displacement of air. :-)

My point exactly, there are natural broadband acoustic phenomena that make
use of large excuursion levels, I don't know why an elephant fart was the
first example that came to mind. :-)

Ok, I'm getting silly
now, but my point is that unless the sound measures something more than
140
dB SPL at the listener's position, it isn't going to cause distortion in
the
hearing mechanism

Distortion at the biological level sets in much sooner than
your numbers indicate.

Most of what I've read on the subject says the human hearing mechanism
doesn't develop overload distortion until 130+ to 140+ dB SPL at low
frequency levels especially.


Yes, but my position is that the distortion you're describing isn't
Doppler
related, or not directly, anyway. There may be some subtle relation,
howev er.

Whatever it is, it's all there is.

[snip]

I have no idea what all this might have to do with "Doppler distortion",
I
just thought some of it might have some relevance to some part of this
discussion.

None. We are discussing IM distortion occuring in a linear
medium due to source motion. Distortion due to being in a
regime where the pressure and velocity of air are not
related linearly is a whole 'nuther discussion.

Ok, but my position is that in a speaker reproducing music under normal
conditions, the source is not moving because the source isn't the cone's
surface, it's the center of excursion. In that case, the IM distortion, if
present, would result from non-linearities of the cone's motion it the
linear medium. This is my opinion, and that certainly doesn't make it fact,
but it seems that the postulation of the existance of Doppler shift in a
speaker depends on the assumption that the moving cone's surface is the
virtual sound source. If that isn't true, then none of the math based on
taht assumption is relevant.

"The Ghost" wrote in message
om...
"Porky" wrote in message news:NIP8d.267327$% doesn't


An elephant fart may exceed 90 dB SPL at ten feet,

I would guess that you reached that conclusion from personal
experience and that it is based on numerous observations.


Not bad, for an amateur, but in actuality I read it in National
Geographic, while in the midst of looking for pictures of topless native
women, back when I was a kid.

and the elephant's
anus is smaller in diameter than an eight inch woofer.

I wouldn't be surprised if the diameter of an elephant's anus is about
the same diameter as your mouth. Furthermore, it would seem that
diameter isn't the only thing that your mouth and an elephant's anus
have in common.

Ah, you're improving, that one was pretty good, and from the character
and quality of your posts, I deduce that your mouth and a male bovine's anus
have much in common as well. Both produce pure bull****.

"Jim Carr" wrote in message
news:8SV8d.17$_a3.16@fed1read05...
"Laurence Payne" wrote in message
...
On Tue, 5 Oct 2004 23:50:59 -0700, "Jim Carr"
wrote:

How can the brain "compensate" for a sound when it requires knowing the
sound in advance? Nobody is arguing that the brain cannot compare two
sounds. However, your notion that somehow the brain could possibly mask
Doppler distortion in such a way as to make it inaudible strikes me as
silly.


The brain is remarkably good at focusing on data and ignoring
distortion. I'm sure Doppler distortion isn't immune to this
principle.

There's a difference between critical listening masking out sounds and
Porky's rather dubious "either/or" claim that the reason we can't hear
Doppler distortion is because the brain is automatically compensating for
it. The former is a matter of concentration and experience. The latter is
magic.

Now you're getting a bit far afield. I explained that I didn't believe that
such a compensation mechanism existed, I merely used the possibility as an
argument against Doppler shift at audible levels in a speaker. I said EITHER
it didn't exist at audible levels, OR because we can't hear it our hearing
mechanism have some method of compensation for it. Since it seems obvious
that there is no such mechanism, it must mean that Doppler distortion
doesn't reach audible levels.

"Porky" wrote in message et...
"Paul Draper" wrote in message
om...
Actually, this isn't quite right. The pressure fluctuations that
correspond to a sound wave don't match with the *position* profile of
the speaker, but with the *velocity* profile of the speaker. Thus the
requirement of a square wave (in pressure) is that the speaker
instantaneously accelerate to its maximum velocity, proceed from one
end of its throw to the other at constant (maximum) velocity, and then
at the other end of the throw instantaneously accelerate to maximum
negative velocity. The way to think about the motion under such a
circumstance is like the little ball in a Pong game. For just the
reason you mention, real speakers won't achieve that hard,
instantaneous bounce at the extrema, but this sure isn't the same as
the even more extreme motion you describe.


In order to accurately reproduce a square wave, the time required for the
cone to travel from its negative excursion to its positive excursion must
equal the rise time of the square wave, and since a perfect square wave has
a rise time of zero the travel would have to be instantaneous. By "excursion
limit" in my previous post, I did not mean the speaker's excursion limits, I
meant the amount of excursion necessary to reproduce the wave at the desired
volume.

I think you're missing the point. The square wave is NOT the plot of
the *position* of the diaphragm as a function of time, it's a plot of
the *velocity* of the diaphragm as a function of time. If you want to
know what the position plot of the diaphragm looks like, you have to
take the integral of the square wave. The integral of a square wave is
a triangle wave. A triangle wave does not demand instantaneous travel
(momentarily infinite speeds), but it does demand an instantaneous
reversal of direction, also something that is not practically
achievable.

Now if you DID try to drive a speaker's POSITION with a square wave
function, then you would be absolutely right.

PD

"Paul Draper" wrote in message
om...
"Porky" wrote in message
et...
"Paul Draper" wrote in message
om...
Actually, this isn't quite right. The pressure fluctuations that
correspond to a sound wave don't match with the *position* profile of
the speaker, but with the *velocity* profile of the speaker. Thus the
requirement of a square wave (in pressure) is that the speaker
instantaneously accelerate to its maximum velocity, proceed from one
end of its throw to the other at constant (maximum) velocity, and then
at the other end of the throw instantaneously accelerate to maximum
negative velocity. The way to think about the motion under such a
circumstance is like the little ball in a Pong game. For just the
reason you mention, real speakers won't achieve that hard,
instantaneous bounce at the extrema, but this sure isn't the same as
the even more extreme motion you describe.


In order to accurately reproduce a square wave, the time required for
the
cone to travel from its negative excursion to its positive excursion
must
equal the rise time of the square wave, and since a perfect square wave
has
a rise time of zero the travel would have to be instantaneous. By
"excursion
limit" in my previous post, I did not mean the speaker's excursion
limits, I
meant the amount of excursion necessary to reproduce the wave at the
desired
volume.

I think you're missing the point. The square wave is NOT the plot of
the *position* of the diaphragm as a function of time, it's a plot of
the *velocity* of the diaphragm as a function of time. If you want to
know what the position plot of the diaphragm looks like, you have to
take the integral of the square wave. The integral of a square wave is
a triangle wave. A triangle wave does not demand instantaneous travel
(momentarily infinite speeds), but it does demand an instantaneous
reversal of direction, also something that is not practically
achievable.

Now if you DID try to drive a speaker's POSITION with a square wave
function, then you would be absolutely right.


You're definitely not going to get a square wave out of even the perfect
massless diaphragm speaker by driving it with a triangular wave. In order to
get the fast rise time of the square wave, the diaphragm has to move from
point a to point b in the same time as the rise time of the square wave,
then hold its position until the descending edge is reached, at which time
the diaphragm must move from point b to point a in the same time as the
descent time of the suare wave, holding that position until the rising slope
occurs again. Even if you're in a perfectly sealed ait tight room the result
still won't be a square wave because of the inertia and elascticity of the
air in the room. What you actually get when you try it with a low frequency
squarewave and mic it, is a positive spike at rise and a negative spike at
fall.

"Jim Carr" wrote in message news:s_49d.334$_a3.3@fed1read05...
"ZZBunker" wrote in message
om...

I am snipping your explanation not out of disprespect but simply because I
don't understand a lot of it and I think it exceeds the discussion.

Porky wrote, "the source's motion causes the apparent wavelength of the
sound to shorten." I disagreed. I will try to state my disagreement more
simply: The apparent *frequency* shifts. However, the wavelength either
shifts or it doesn't depending on whether the source if moving.

That's true. But I won't even bother to ask you how
you derived it, since I know you derived it from the
Lorentz Transformation and GPS. But GPS, just by
mere Philosophic coincedence, has the singular mathematical property,
that it in fact has nothing but singular poles,
and is hence musical.

Hence, that's also the reason that real RADAR AND SONAR
Engineers have given it the special name Ground-Tracking Radar,
rather than radar. Since it's what AT&T and Musicians
do, rather than what Engineers do.




Suppose I have a machine that sends a ball rolling in a straight line at 10
feet per second. I launch one ball per second. I think we would agree that
the balls are 10 feet apart. Now, if I move my machine at 5 feet per second
in the same direction as the balls, then each ball will be five feet apart.
That's the wavelength.

That is the MATHEMATICAL *DEFINITION* of LENGTH.
Which is also why Einstein rediscovered the
concept of MASS-ENERGY, to prove to mathematicians,
that time is also a part of the sound "equation".

Since what you just descibed is nothing other than
the Huygens Principle, combined with Wavelets.

If you move fireballs 10 feet per second in the
direction of the sun, and then move a machine
at 5 feet per second in the direction of the
balls you will get a completely difference answer
for the wavelength than if the sun moved the
fireballs 10 per second at you. Since the sun
seems to know much more about angular momemtum
than Quantum Mechanics does.






Frequency is a different matter. If there is a wall some distance away, the
balls launched from the stationary machine will hit the wall a frequency of
one per second. In the second case the balls will strike the wall at one per
half second until eventually my machine crashes into the wall and I lose my
government grant.

If in the first scenario I move the wall at 2 feet per second towards the
oncoming balls, the balls will strike the wall at a frequency of one every
0.8 seconds. I still say the balls are 10 feet apart. The frequency changed
because the wall was moving, but distance between the balls didn't change.

If the balls traveled down a lane that had a line painted once per foot, and
I took a snapshot of the balls, I could clearly see that they were 10 feet
apart.

I think that to describe Doppler shift accurately one should state that the
apparent frequency shifts in all cases but that the wavelength only changes
if the source is moving. Our ears only measure frequency so the net effect
is the same.

Would you agree or disagree with this explanation?

Well, since you seem to be trying to explain Differential Geometry
and Topology, rather than sound, I'll have to let you have the
floor. But the inherent problem with Topological explanations of sound,
it that they inevitably attrach only the CIA,
rather than musicians.

On 7 Oct 2004 08:43:28 -0700, (Paul Draper) wrote:

"Porky" wrote in message et...
"Paul Draper" wrote in message
om...
Actually, this isn't quite right. The pressure fluctuations that
correspond to a sound wave don't match with the *position* profile of
the speaker, but with the *velocity* profile of the speaker. Thus the
requirement of a square wave (in pressure) is that the speaker
instantaneously accelerate to its maximum velocity, proceed from one
end of its throw to the other at constant (maximum) velocity, and then
at the other end of the throw instantaneously accelerate to maximum
negative velocity. The way to think about the motion under such a
circumstance is like the little ball in a Pong game. For just the
reason you mention, real speakers won't achieve that hard,
instantaneous bounce at the extrema, but this sure isn't the same as
the even more extreme motion you describe.


In order to accurately reproduce a square wave, the time required for the
cone to travel from its negative excursion to its positive excursion must
equal the rise time of the square wave, and since a perfect square wave has
a rise time of zero the travel would have to be instantaneous. By "excursion
limit" in my previous post, I did not mean the speaker's excursion limits, I
meant the amount of excursion necessary to reproduce the wave at the desired
volume.

I think you're missing the point. The square wave is NOT the plot of
the *position* of the diaphragm as a function of time, it's a plot of
the *velocity* of the diaphragm as a function of time.

.. . or *acceleration* perhaps?

If you want to
know what the position plot of the diaphragm looks like, you have to
take the integral of the square wave. The integral of a square wave is
a triangle wave. A triangle wave does not demand instantaneous travel
(momentarily infinite speeds), but it does demand an instantaneous
reversal of direction, also something that is not practically
achievable.

Now if you DID try to drive a speaker's POSITION with a square wave
function, then you would be absolutely right.

PD

On Wed, 06 Oct 2004 15:54:21 -0700, Bob Cain
wrote:



Goofball_star_dot_etal wrote:

On Wed, 06 Oct 2004 11:26:51 -0700, Bob Cain
wrote:


It is the only distortion phenomenon that follows from the
motion of the source, so call it what you wish. That its
magnitude is a minimum, zero, when the velocity due to the
LF is a maximum just belies the usual picture people have of
what is going on and the way it is often described.


The Elliot Effect?

Yes. IIRC, his test shows exactly that.


Well, I am not particularly keen to trash his work in public, behind
his back but aren't you just a teeny weeny bit concerned that to reach
the conclusuion that he does, that he really needs to know the
position of the speaker cone in relation to the frequency/phase
modulation? And you a self-proclaimed scientist and all.

Goofball_star_dot_etal wrote:

Well, I am not particularly keen to trash his work in public, behind
his back but aren't you just a teeny weeny bit concerned that to reach
the conclusuion that he does, that he really needs to know the
position of the speaker cone in relation to the frequency/phase
modulation? And you a self-proclaimed scientist and all.

I admit I haven't gone back to look at it again in detail
and I will. That's why I said IIRC. Perhaps I don't


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Porky" wrote in message et...
"ZZBunker" wrote in message
.. .
"Jim Carr" wrote in message
news:S%V8d.19$_a3.8@fed1read05...
"ZZBunker" wrote in message
om...

It is all relativistic mumno-jumbo, from Einstein's
train experiment to the speaker diaphrams. The brain
has nothing to do with light or sound. It's
the geometric relationship bewteen eye sockets,
ear sockets, and wind that create the sound.

It was Doppler's train experiment, not Einstein's.

No ****. And it was Einstein's photon and Bose shift experiments,
and not some morons from physics, Beatle acid land,
and Florida Radio Shack "wavelength" DOOFUS--VILLE,
that made was it known as over-pressure,
for the Micheal Jackson train idiots in
the idiot land, known as Los Angelos
and Feynmann-ville.





I think you talking about music though, not sound though.
The "speed" of sound, and the Doppler Shift only exist
in the context of music, where the medium is
locally linear. Most mediums, including the
Earth's crust, the Ocean Bottom, clouds, and the sun's
photosphere don't have a fixed speed of sound.
So the "wavelength" in those media doesn't
really exist in the Classical Fourier sense. Which
is why you need complex frequencies in those cases.
And the imaginary part of the frequency
is going to be traveling through a different state of matter
than the real part of the frequency.
And it's going to travel infinitely faster
than the real part. Which is where matrix mechanics
and the Uncertainty Prinicple came from.


The Heisenberg uncertainty principle pertains to subatomic particle physics.
It has nothing to do with sound.

Since I said I said the "Uncertainty Principle,
and not Heisenburg, it's only concerns Gauss,
rather then Newton or Einstein.

As he himself would have told "Physicsts".

It's all in the wristen. --- Herr Commies!!





And what the wavelength is in a matrix,
nobody knows.


Again, nothing to do with the real world.

The last time matrices didn't concern the
real world, was the last time Hawking
did concern the real world. Which was the
last time entropy actually existed,
which was never.



And Einstein was right about the measuring sticks.
They're only useful where you have a source and receiver.
But the Mercury Perehelion measurement doesn't
have a source receiver mode.

Rest snipped. Since it only concerns
Carl Sagan, and assorted idiots from
the UFO Contact Multi-verse, rather than
music, science, machines, or intelligence.

On Thu, 07 Oct 2004 10:38:57 -0700, Bob Cain
wrote:



Goofball_star_dot_etal wrote:

Well, I am not particularly keen to trash his work in public, behind
his back but aren't you just a teeny weeny bit concerned that to reach
the conclusuion that he does, that he really needs to know the
position of the speaker cone in relation to the frequency/phase
modulation? And you a self-proclaimed scientist and all.

I admit I haven't gone back to look at it again in detail
and I will. That's why I said IIRC. Perhaps I don't



Fair enough. I am going from memory myself. At first I thought it
looked quite promising but after a while it started to hurt to read it

"Boy, Rod deserves a medal for the two most recent articles!"
-Christopher Witmer
http://www.instantboard.com/users/ro...hlight=doppler

" Rod Elliot has just recently done some an experiment that
vanquishes one of the supposed causes, the dynamic doppler
shift of a HF wave due to the velocity of a superimposed LF
wav. It just doesn't happen. See:
http://sound.westhost.com/doppler.htm " - Bob Cain

Concentrate on this although there are about half a dozen things I am
not happy about:

He records two "voltages*.
The first is the speaker drive voltage. This is related to the
speaker motion from voltage to current through the impedence and from
current to force. Well above resonance where mass dominates the
acceleration is in phase and proportional to applied voltage, at
resonance where the reactance is zero the velocity is proportional to
voltage and below resonance where the stiffness or complience
dominates the displacement is proportional to voltage. He does not
attempt to use this information to determine position. Instead he uses
the change in phase about resonance to align the waveform of *voltage*
from the mic with the drive voltage at 50?Hz without the HF carrier
and he uses the phase shift with distance from the mic to align the HF
signal without the 50Hz so that this drive voltage can be used as a
reference with which to compare the microphone waveform when both
frequencies are present. (From memory!)

The other *voltage* he records is from the micriophone after
amplification. This is related to the pressure at the microphone. He
does not (from memory) measure the phase relationship between pressure
and voltage or between pressure and cone displacement.

He writes(I forced myself to look!):
"It is quite apparent that there is no shift at the LF zero-crossing
point, and since this is the area where cone velocity is highest, it
is obvious that Doppler effect is not the culprit."
He is saying that the pressure ( mic voltage actually) is zero at
maximum cone velocity. No proof.

I have my own graph of normalized cone displacement, phase shift,
frequency shift and LF pressure from the Arny Data(tm) but the work is
incomplete. It seems to be saying that mic output voltage at 50Hz is
following the cone velocity more closely than cone displacement. The
way I derived the phase of displacement was a bit too cunning for its
own good so I will keep quiet about it and note that neither of us has
a direct measurement of the cone position.

Porky wrote:


Ok, but my position is that in a speaker reproducing music under normal
conditions, the source is not moving because the source isn't the cone's
surface, it's the center of excursion.

Either can be considered the source because both are
reproduced exactly at any point distant from it. The kicker
is that there is a non-linear relationship between the
motion of a particle mormally at rest at a point and the
fluid velocity and corresponding pressure at that point. In
a tube both are identical to the conditions at the rest
position of the driver at a time d/c in the past. It is the
non-linear relationship between these two types of motion,
one *with respect to* and one *at* a given point, that gives
rise to the IM products.

Since the motion of the speaker is what is controlled, the
motion of a particle at a distance about its rest position
is where the undistorted signal lies. What we measure with
a microphone at that rest position is a distorted version of
the signal.

This is why it is meaningless to talk about distortion due
to natural sources. All of that interaction is part and
parcel of its creation but when we start talking about
reproducing a natural sound with a moving driver, there will
be the added reproduction distortion due to the difference
between the driver motion and the motion that is measured.

If our microphones measured the velocity of the particles
normally at rest at its position rather than the
velocity/pressure of whatever particle happens to be at its
position, there would be no distortion in the reproduction.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Porky" wrote in
:

Ah, you're improving, that one was pretty good, and from the
character
and quality of your posts,

I am glad that you recognize and appreciate the improvement. Since the
character and quality of your posts served as the benchmark, you are really
the one who rightfully deserves credit for the improvement.


I deduce that your mouth and a male
bovine's anus have much in common as well.

I had no idea that swine were either capable of deduction or were so
knowledgable about the male bovine anus. No doubt you are quite adept at
servicing all of the male bovine that line up at the swine pen on a daily
basis. What other farm animals suit your fancy?


Both produce pure bull****.

Bulls see red. Swine see bull****. Neither correctly see reality.

"ZZBunker" wrote in message
om...
"Porky" wrote in message
et...
"ZZBunker" wrote in message
.. .
"Jim Carr" wrote in message
news:S%V8d.19$_a3.8@fed1read05...
"ZZBunker" wrote in message
om...

It is all relativistic mumno-jumbo, from Einstein's
train experiment to the speaker diaphrams. The brain
has nothing to do with light or sound. It's
the geometric relationship bewteen eye sockets,
ear sockets, and wind that create the sound.

It was Doppler's train experiment, not Einstein's.

No ****. And it was Einstein's photon and Bose shift experiments,
and not some morons from physics, Beatle acid land,
and Florida Radio Shack "wavelength" DOOFUS--VILLE,
that made was it known as over-pressure,
for the Micheal Jackson train idiots in
the idiot land, known as Los Angelos
and Feynmann-ville.





I think you talking about music though, not sound though.
The "speed" of sound, and the Doppler Shift only exist
in the context of music, where the medium is
locally linear. Most mediums, including the
Earth's crust, the Ocean Bottom, clouds, and the sun's
photosphere don't have a fixed speed of sound.
So the "wavelength" in those media doesn't
really exist in the Classical Fourier sense. Which
is why you need complex frequencies in those cases.
And the imaginary part of the frequency
is going to be traveling through a different state of matter
than the real part of the frequency.
And it's going to travel infinitely faster
than the real part. Which is where matrix mechanics
and the Uncertainty Prinicple came from.


The Heisenberg uncertainty principle pertains to subatomic particle
physics.
It has nothing to do with sound.

Since I said I said the "Uncertainty Principle,
and not Heisenburg, it's only concerns Gauss,
rather then Newton or Einstein.

As he himself would have told "Physicsts".

It's all in the wristen. --- Herr Commies!!





And what the wavelength is in a matrix,
nobody knows.


Again, nothing to do with the real world.

The last time matrices didn't concern the
real world, was the last time Hawking
did concern the real world. Which was the
last time entropy actually existed,
which was never.



And Einstein was right about the measuring sticks.
They're only useful where you have a source and receiver.
But the Mercury Perehelion measurement doesn't
have a source receiver mode.

Rest snipped. Since it only concerns
Carl Sagan, and assorted idiots from
the UFO Contact Multi-verse, rather than
music, science, machines, or intelligence.

Hmmm, must be some heavy acid this dude is on! :-)

"Bob Cain" wrote in message
...


Porky wrote:


Ok, but my position is that in a speaker reproducing music under
normal
conditions, the source is not moving because the source isn't the cone's
surface, it's the center of excursion.

Either can be considered the source because both are
reproduced exactly at any point distant from it. The kicker
is that there is a non-linear relationship between the
motion of a particle mormally at rest at a point and the
fluid velocity and corresponding pressure at that point. In
a tube both are identical to the conditions at the rest
position of the driver at a time d/c in the past. It is the
non-linear relationship between these two types of motion,
one *with respect to* and one *at* a given point, that gives
rise to the IM products.

Since the motion of the speaker is what is controlled, the
motion of a particle at a distance about its rest position
is where the undistorted signal lies. What we measure with
a microphone at that rest position is a distorted version of
the signal.

This is why it is meaningless to talk about distortion due
to natural sources. All of that interaction is part and
parcel of its creation but when we start talking about
reproducing a natural sound with a moving driver, there will
be the added reproduction distortion due to the difference
between the driver motion and the motion that is measured.

If our microphones measured the velocity of the particles
normally at rest at its position rather than the
velocity/pressure of whatever particle happens to be at its
position, there would be no distortion in the reproduction.


But that isn't due to Doppler shift.... is it? I really think if it isn't
Doppler shift, it shouldn't be called Doppler distortion. Maybe non-linear
particle motion distortion would be a better label. :-)

ow (Goofball_star_dot_etal) wrote in
:

Well, I am not particularly keen to trash his work in public, behind
his back but aren't you just a teeny weeny bit concerned that to reach
the conclusuion that he does, that he really needs to know the
position of the speaker cone in relation to the frequency/phase
modulation? And you a self-proclaimed scientist and all.


Bob Cain can call himself whatever he wants. However, not only is he not a
scientist, he is not even a c-grade engineer, which is evident from the
fact that he is so technically inept that he had to come to sci.physics
begging someone to spoon feed him through the trivial solution of an
elementary one-dimensional wave equation which is discussed in virtually
every introductory textbook on acoustics. Worse yet, he is still making up
and using meaningless terminology and pulling clearly incorrect equations
out of thin air, so he still doesn't understand the solution that he was
spoon fed.

in article , The Ghost at
wrote on 10/7/04 8:49 PM:

ow (Goofball_star_dot_etal) wrote in
:

Well, I am not particularly keen to trash his work in public, behind
his back but aren't you just a teeny weeny bit concerned that to reach
the conclusuion that he does, that he really needs to know the
position of the speaker cone in relation to the frequency/phase
modulation? And you a self-proclaimed scientist and all.


Bob Cain can call himself whatever he wants. However, not only is he not a
scientist, he is not even a c-grade engineer, which is evident from the
fact that he is so technically inept that he had to come to sci.physics
begging someone to spoon feed him through the trivial solution of an
elementary one-dimensional wave equation which is discussed in virtually
every introductory textbook on acoustics. Worse yet, he is still making up
and using meaningless terminology and pulling clearly incorrect equations
out of thin air, so he still doesn't understand the solution that he was
spoon fed.



And that's the charitable explanation! ;-)

"The Ghost" wrote in message
. 6...
"Porky" wrote in
:

Ah, you're improving, that one was pretty good, and from the
character
and quality of your posts,

I am glad that you recognize and appreciate the improvement. Since the
character and quality of your posts served as the benchmark, you are
really
the one who rightfully deserves credit for the improvement.


Thank you! Your decency and kindness are matched only by your intelligence,
and your wit, Zero equals zero, in other words.

I deduce that your mouth and a male
bovine's anus have much in common as well.

I had no idea that swine were either capable of deduction or were so
knowledgeable about the male bovine anus. No doubt you are quite adept at
servicing all of the male bovine that line up at the swine pen on a daily
basis. What other farm animals suit your fancy?

The sum of what I know about a male bovine's anus is that it produces the
same thing your mouth does, bull****. As for what other farm animals I like,
that would be all of them, as long as they're properly cooked and served
with the appropriate side dishes.


Bulls see red. Swine see bull****. Neither correctly see reality.

And ghosts, being nonexistent, are not a part of reality, therefore they
cannot properly perceive reality, but we can see right through you.

"Porky" wrote in
:


"The Ghost" wrote in message
. 6...
"Porky" wrote in
:

Ah, you're improving, that one was pretty good, and from the
character
and quality of your posts,

I am glad that you recognize and appreciate the improvement. Since
the character and quality of your posts served as the benchmark, you
are
really
the one who rightfully deserves credit for the improvement.


Thank you! Your decency and kindness are matched only by your
intelligence, and your wit, Zero equals zero, in other words.

I deduce that your mouth and a male
bovine's anus have much in common as well.

I had no idea that swine were either capable of deduction or were so
knowledgeable about the male bovine anus. No doubt you are quite
adept at servicing all of the male bovine that line up at the swine
pen on a daily basis. What other farm animals suit your fancy?

The sum of what I know about a male bovine's anus is that it
produces the
same thing your mouth does, bull****. As for what other farm animals I
like, that would be all of them, as long as they're properly cooked
and served with the appropriate side dishes.


Bulls see red. Swine see bull****. Neither correctly see reality.

And ghosts, being nonexistent, are not a part of reality, therefore
they
cannot properly perceive reality, but we can see right through you.


Thank you for this and your other enlightening series of exchanges. You
have provided me with a great deal of insight into the mindset of the more
technically-inept regulars in the audio groups. I now have at least some
appreciation for why the level of technical discourse in the audio groups
has been and continues to be so pathetic and abysmal.

"The Ghost" wrote in message
. 7...
"Porky" wrote in
:


"The Ghost" wrote in message
. 6...
"Porky" wrote in
:

Ah, you're improving, that one was pretty good, and from the
character
and quality of your posts,

I am glad that you recognize and appreciate the improvement. Since
the character and quality of your posts served as the benchmark, you
are
really
the one who rightfully deserves credit for the improvement.


Thank you! Your decency and kindness are matched only by your
intelligence, and your wit, Zero equals zero, in other words.

I deduce that your mouth and a male
bovine's anus have much in common as well.

I had no idea that swine were either capable of deduction or were so
knowledgeable about the male bovine anus. No doubt you are quite
adept at servicing all of the male bovine that line up at the swine
pen on a daily basis. What other farm animals suit your fancy?

The sum of what I know about a male bovine's anus is that it
produces the
same thing your mouth does, bull****. As for what other farm animals I
like, that would be all of them, as long as they're properly cooked
and served with the appropriate side dishes.


Bulls see red. Swine see bull****. Neither correctly see reality.

And ghosts, being nonexistent, are not a part of reality, therefore
they
cannot properly perceive reality, but we can see right through you.


Thank you for this and your other enlightening series of exchanges. You
have provided me with a great deal of insight into the mindset of the more
technically-inept regulars in the audio groups. I now have at least some
appreciation for why the level of technical discourse in the audio groups
has been and continues to be so pathetic and abysmal.

You're welcome! I appreciate the sincerity of your sarcasm. Unfortunately
for you, ghosts don't real brains, so they don't have insights either. On
the other hand, even swine have minds with which to have mindsets. As for
technical ineptness, you have shown so little technical knowledge here that
the term "inept" would be a profound compliment if used in reference to you.
The discourse only sounds pathetic and abysmal to you because it's so far
over your head.

"Porky" wrote in message
t...

It was Doppler's train experiment, not Einstein's.

You've obviously never read "Relativity - The Special and General Theory" by
some old guy named Albert Einstein. He only mentions the train and
embankment about a zillion times.

"Porky" wrote in message
t...

Now you're getting a bit far afield. I explained that I didn't believe
that
such a compensation mechanism existed, I merely used the possibility as an
argument against Doppler shift at audible levels in a speaker.

What the hell does that mean? You don't believe something is possible yet
you offer it as an alternative explanation to Doppler distortion existing at
audible levels? Personally, I think either it's not audible or the CIA has
implanted a chip in my head that convinces me I don't hear it.

What a maroon.

Porky wrote:

But that isn't due to Doppler shift.... is it? I really think if it isn't
Doppler shift, it shouldn't be called Doppler distortion. Maybe non-linear
particle motion distortion would be a better label. :-)

It doesn't look like what would be expected of Doppler
shift, that the distortion be the greatest at maximum LF
velocity and the minimum at zero velocity. It looks the
opposite of that. You won't see me crusading for a name
change anytime soon, however. :-)

It is, however, a phase modulation which is also what
Doppler shift is.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Porky wrote:

The discourse only sounds pathetic and abysmal to you because it's so far
over your head.

He has, really, no other place for it to go.

Uncle Al says, "The first requirement for dealing with
reality is recognizing it."

Gary should pay attention to Uncle Al but, alas, he is a
component of reality.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Porky" wrote in message
t...

Look at the equations, if "F" = frequency, "W" = wavelength, and "C" = the
speed that waves travel in the medium, then F=C/W, and W=C/F. The
relationship is absolute, that's why your machine/ball analogy doesn't
apply.

Okay, let's look at your formula.

For our purposes the waves travel at 80 feet per second. I have a stationary
source emitting waves at 10 per second. So, as you say, W=80/10. Therefore,
we have a wavelength of 8, right?

My receiver is moving towards the source at 50 feet per second. We know then
that the *apparent* frequency is 16.25 because AF=10((80+50)/80) (Apparent
Frequency from Doppler formula). So, W=80/16.25 which is a wavelength of
roughly 4.92, right?

How can that be, Porky? It started out at as 8 and now it's around 5? How
can the same waves have two different wavelengths? They don't! The
wavelength didn't change just because the receiver was moving. You believe
in the Doppler Effect, don't you? We can easily envision how the apparent
frequency is different if the receiver is moving.

So what's wrong? The problem is that your formula does not take into
consideration the movement of the receiver. Let's do that. Thus W=C/F
becomes W=(C+R)/F where R is the speed of the Receiver. So, we get
W=(80+50)/16.25, which gives us a wavelength of 8, just like at the source!
Hot damn!!

If we measure the wavelength at the source, then the movement of receiver
*relative* to the source is always zero, so the formula still works. But you
still have to use the Doppler formula to determine the frequency if your
source is moving. In our case we get AF=10(80/(80-50), which is 26.66. Thus,
the wavelength is 80/26.66, which is 3.

In other words when the source is stationary, the wavelength is 8. If the
receiver moves the wavelength is still 8. If the source moves, the
wavelength is 3.

Thus, my previous statement is proved: The apparent frequency shifts in all
cases but the wavelength only changes if the source is moving.

I have no training or experience in physics or acoustics (well, I play
acoustic guitar), so pardon me if my formulas don't use the correct terms or
if I accidentally misplaced some parentheses.

On Thu, 07 Oct 2004 15:28:26 -0700, Bob Cain
wrote:

Since the motion of the speaker is what is controlled, the
motion of a particle at a distance about its rest position
is where the undistorted signal lies. What we measure with
a microphone at that rest position is a distorted version of
the signal.

So, wher's the Doppler?

"Porky" wrote in message et...
"Paul Draper" wrote in message
om...


I think you're missing the point. The square wave is NOT the plot of
the *position* of the diaphragm as a function of time, it's a plot of
the *velocity* of the diaphragm as a function of time. If you want to
know what the position plot of the diaphragm looks like, you have to
take the integral of the square wave. The integral of a square wave is
a triangle wave. A triangle wave does not demand instantaneous travel
(momentarily infinite speeds), but it does demand an instantaneous
reversal of direction, also something that is not practically
achievable.

Now if you DID try to drive a speaker's POSITION with a square wave
function, then you would be absolutely right.


You're definitely not going to get a square wave out of even the perfect
massless diaphragm speaker by driving it with a triangular wave. In order to
get the fast rise time of the square wave, the diaphragm has to move from
point a to point b in the same time as the rise time of the square wave,
then hold its position until the descending edge is reached, at which time
the diaphragm must move from point b to point a in the same time as the
descent time of the suare wave, holding that position until the rising slope
occurs again. Even if you're in a perfectly sealed ait tight room the result
still won't be a square wave because of the inertia and elascticity of the
air in the room. What you actually get when you try it with a low frequency
squarewave and mic it, is a positive spike at rise and a negative spike at
fall.


We're talking at crossed purposes here, and I suppose it depends on
what you are measuring when you look at the scope and see a square
wave. There are several possibilities:
1. The voltage applied across the terminals of the speaker coil.
2. The current driven through the speaker coil
3. The position of the speaker coil
4. The velocity of the speaker coil
5. The acceleration of the speaker coil
6. The pressure in the air at a point in front of the speaker
diaphragm

I've been arguing that there is a connection between 4 and 6. Those
two, I think, follow the same profile. The others are related through
derivatives or integrals, possibly with a phase shift.

PD

Vladan wrote:

On Thu, 07 Oct 2004 15:28:26 -0700, Bob Cain
wrote:


Since the motion of the speaker is what is controlled, the
motion of a particle at a distance about its rest position
is where the undistorted signal lies. What we measure with
a microphone at that rest position is a distorted version of
the signal.


So, wher's the Doppler?

If the the motion of a test particle normally at rest at a
point is purely sinusoidal and containing two tones then
there is a cross phase modulation of each by the other and
by itself that appears as IM distortion in the fluid
velocity at that same point. It can be called Doppler
because standard Doppler shift can be drived from a constant
modulation of frequency. Or it can be called Billy. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Porky" wrote in message ...

As for
technical ineptness, you have shown so little technical knowledge here that
the term "inept" would be a profound compliment if used in reference to you.

Please feel free to say whatever you want about me because, like
everything else that you have to say, it is irrelevant and of no
practical consequence.


The discourse only sounds pathetic and abysmal to you because it's so far
over your head.

The discourse sounds pathetic and abysmal because in reality it is
pathetic and abysmal, and the reason it is pathetic and abysmal is
because the low-life technically-inept participants are pathetic and
abysmal.

Bob Cain wrote in message ...
Porky wrote:

The discourse only sounds pathetic and abysmal to you because it's so far
over your head.

He has, really, no other place for it to go.

Uncle Al says, "The first requirement for dealing with
reality is recognizing it."

Gary should pay attention to Uncle Al but, alas, he is a
component of reality.

Bob

Any similarity between the Bob Cain & Porky duo and the Beavis &
Butthead duo is, undoubtedly, purely coincidental. Except, I don't
believe that Beavis and Butthead were a couple of fudge packers.

"Paul Draper" wrote in message
om...
"Porky" wrote in message
et...
"Paul Draper" wrote in message
om...


I think you're missing the point. The square wave is NOT the plot of
the *position* of the diaphragm as a function of time, it's a plot of
the *velocity* of the diaphragm as a function of time. If you want to
know what the position plot of the diaphragm looks like, you have to
take the integral of the square wave. The integral of a square wave is
a triangle wave. A triangle wave does not demand instantaneous travel
(momentarily infinite speeds), but it does demand an instantaneous
reversal of direction, also something that is not practically
achievable.

Now if you DID try to drive a speaker's POSITION with a square wave
function, then you would be absolutely right.


You're definitely not going to get a square wave out of even the
perfect
massless diaphragm speaker by driving it with a triangular wave. In
order to
get the fast rise time of the square wave, the diaphragm has to move
from
point a to point b in the same time as the rise time of the square wave,
then hold its position until the descending edge is reached, at which
time
the diaphragm must move from point b to point a in the same time as the
descent time of the suare wave, holding that position until the rising
slope
occurs again. Even if you're in a perfectly sealed ait tight room the
result
still won't be a square wave because of the inertia and elascticity of
the
air in the room. What you actually get when you try it with a low
frequency
squarewave and mic it, is a positive spike at rise and a negative spike
at
fall.


We're talking at crossed purposes here, and I suppose it depends on
what you are measuring when you look at the scope and see a square
wave. There are several possibilities:
1. The voltage applied across the terminals of the speaker coil.
2. The current driven through the speaker coil
3. The position of the speaker coil
4. The velocity of the speaker coil
5. The acceleration of the speaker coil
6. The pressure in the air at a point in front of the speaker
diaphragm

I've been arguing that there is a connection between 4 and 6. Those
two, I think, follow the same profile. The others are related through
derivatives or integrals, possibly with a phase shift.

PD

A pure square wave has zero rise and fall times, the "slopes" are
vertical. If you apply a square wave to a speaker's terminals, when the
positive voltage rise happens, the cone will jump forward and will push the
air in front of it. Because of the inertia of the mass of the cone and the
air in front of it, the cone will not instantly spring to it's maximum
forward position, it will require some period of time, thus the slope of the
soundwave being generated will not have a vertical rise time. The same
applies to the fall time, again, the slope will not be vertical. Also if the
applied square wave is of a low enough frequency, since the average
listening room is not air tight, the "top" and "bottom" of the generated
soundwave will not be level, they will contain a slope even though the
applied electrical square wave has a level "top" and "bottom". As for item
(4), in order to follow the square wave's zero rise time, the cone's
velocity would have to be infinite, and that can't happen. There is a direct
relationship between the velocity of the cone and the rate of change in
pressure, so there is a connection between (4) and (6). If one were to apply
say, a 20 Hz square wave to a speaker, and record the resulting sound wave,
one would see a positive sawtooth wave corresponding to the rise of the wave
with a rather abrupt (but not vertical) positive slope and a more gradual
negative slope, and then a negative sawtooth wave corresponding to the fall
of the wave with a rather abrupt (but not vertical) negative slope and a
more gradual positive slope. This is what happens in a real world speaker
placed in a real world typical listening room. At higher frequencies, it is
possible to reproduce a fair approximation of a square wave, but not a true
pure square wave.

"Jim Carr" wrote in message
news:jJp9d.3557$_a3.1033@fed1read05...
"Porky" wrote in message
t...

It was Doppler's train experiment, not Einstein's.

You've obviously never read "Relativity - The Special and General Theory"
by
some old guy named Albert Einstein. He only mentions the train and
embankment about a zillion times.

But since this thread is about Doppler shift in a speaker, Doppler's train
experiment is the more relevant one, is it not?

"Jim Carr" wrote in message
news:37s9d.4659$_a3.4526@fed1read05...
"Porky" wrote in message
t...

Look at the equations, if "F" = frequency, "W" = wavelength, and "C" =
the
speed that waves travel in the medium, then F=C/W, and W=C/F. The
relationship is absolute, that's why your machine/ball analogy doesn't
apply.

Okay, let's look at your formula.

For our purposes the waves travel at 80 feet per second. I have a
stationary
source emitting waves at 10 per second. So, as you say, W=80/10.
Therefore,
we have a wavelength of 8, right?

My receiver is moving towards the source at 50 feet per second. We know
then
that the *apparent* frequency is 16.25 because AF=10((80+50)/80) (Apparent
Frequency from Doppler formula). So, W=80/16.25 which is a wavelength of
roughly 4.92, right?

How can that be, Porky? It started out at as 8 and now it's around 5? How
can the same waves have two different wavelengths? They don't! The
wavelength didn't change just because the receiver was moving. You believe
in the Doppler Effect, don't you? We can easily envision how the apparent
frequency is different if the receiver is moving.

So what's wrong? The problem is that your formula does not take into
consideration the movement of the receiver. Let's do that. Thus W=C/F
becomes W=(C+R)/F where R is the speed of the Receiver. So, we get
W=(80+50)/16.25, which gives us a wavelength of 8, just like at the
source!
Hot damn!!

If we measure the wavelength at the source, then the movement of receiver
*relative* to the source is always zero, so the formula still works. But
you
still have to use the Doppler formula to determine the frequency if your
source is moving. In our case we get AF=10(80/(80-50), which is 26.66.
Thus,
the wavelength is 80/26.66, which is 3.

In other words when the source is stationary, the wavelength is 8. If the
receiver moves the wavelength is still 8. If the source moves, the
wavelength is 3.

Thus, my previous statement is proved: The apparent frequency shifts in
all
cases but the wavelength only changes if the source is moving.

I have no training or experience in physics or acoustics (well, I play
acoustic guitar), so pardon me if my formulas don't use the correct terms
or
if I accidentally misplaced some parentheses.

Wavelength and frequency are directly related and in any medium where the
velocity of propagation is constant, as with sound, if one changes, the
other has to change as well and the change will be directly proportional,
there are no exceptions. One thing you're overlooking is that if the
receiver is moving, in order to make a valid observation about what he
observes, your measuring device has to be moving with him, so the apparent
wavelength he sees changes with his velocity and direction just as it does
when the source is moving relative to him, and the change in frequency he
observes will be proportional to the change in wavelength he observes. It is
all relative, it really isn't the absolute velocity of the source or the
receiver, it's the relative velocity between them, and it doesn't matter
which one is moving as far as the receiver's observations are concerned.
To make it even more confusing, if you are traveling at a different
velocity and direction relative to the source than is the receiver, you'll
observations will be totally different than his.

"Bob Cain" wrote in message
...


Porky wrote:

But that isn't due to Doppler shift.... is it? I really think if it
isn't
Doppler shift, it shouldn't be called Doppler distortion. Maybe
non-linear
particle motion distortion would be a better label. :-)

It doesn't look like what would be expected of Doppler
shift, that the distortion be the greatest at maximum LF
velocity and the minimum at zero velocity. It looks the
opposite of that. You won't see me crusading for a name
change anytime soon, however. :-)

It is, however, a phase modulation which is also what
Doppler shift is.

I agree with that. I just think a more appropriate label should be applied.
Why blame it on poor old Mr Doppler? :-)

"Bob Cain" wrote in message
...


Vladan wrote:

On Thu, 07 Oct 2004 15:28:26 -0700, Bob Cain
wrote:


Since the motion of the speaker is what is controlled, the
motion of a particle at a distance about its rest position
is where the undistorted signal lies. What we measure with
a microphone at that rest position is a distorted version of
the signal.


So, wher's the Doppler?

If the the motion of a test particle normally at rest at a
point is purely sinusoidal and containing two tones then
there is a cross phase modulation of each by the other and
by itself that appears as IM distortion in the fluid
velocity at that same point. It can be called Doppler
because standard Doppler shift can be drived from a constant
modulation of frequency. Or it can be called Billy. :-)


Or how about calling it "Bob" distortion? *LOL*

"The Ghost" wrote in message
om...
Bob Cain wrote in message
...
Porky wrote:

The discourse only sounds pathetic and abysmal to you because it's so
far
over your head.

He has, really, no other place for it to go.

Uncle Al says, "The first requirement for dealing with
reality is recognizing it."

Gary should pay attention to Uncle Al but, alas, he is a
component of reality.

Bob

Any similarity between the Bob Cain & Porky duo and the Beavis &
Butthead duo is, undoubtedly, purely coincidental. Except, I don't
believe that Beavis and Butthead were a couple of fudge packers.

My wife used to be a fudge packer, she managed a fudge store that did a
brisk mail order business, so she packed fudge for shipment every day. I've
never packed fudge though.
BTW the "Gray Ghost" (John Singleton Mosby) was a part of Civil War
history, but now we apparently have the "Gay Ghost" invading the audio news
groups, which should not be surprising since ghosts are commonly thought to
hide in closets. :-)

"Jim Carr" wrote in message
news:erq9d.3701$_a3.305@fed1read05...
"Porky" wrote in message
t...

Now you're getting a bit far afield. I explained that I didn't believe
that
such a compensation mechanism existed, I merely used the possibility as
an
argument against Doppler shift at audible levels in a speaker.

What the hell does that mean? You don't believe something is possible yet
you offer it as an alternative explanation to Doppler distortion existing
at
audible levels? Personally, I think either it's not audible or the CIA has
implanted a chip in my head that convinces me I don't hear it.

What a maroon.

Oh, I see now, you're going back to the same old crap just because I had a
disagreement with Arny. Keep in mind that Arny was the one who started using
labels like "stupid" and "ignorant" just because he apparently couldn't see
that I made it clear that our informal experiment wasn't scientifically
valid and that I was stating opinion, not hard fact. He insulted me, so I
returned the favor. You might want to note that I apologized to him for
doing so, even though he made no apology, in an attempt to preserve harmony
in the group. I wasn't really trying to argue about Arny's qualifications
concerning scientific testing, I was ticked because he ignored my
disclaimers about the lack of scientific validity in our experiment and
chose to insult me.

Here's my original statement: If Doppler distortion actually exists at
the levels postulated (I believe the amount 26% was posted), then the human
hearing must have a mechanism to compensate for it because we don't hear it.
My personal take on it is that if Doppler distortion does exist it is at
inaudible levels.
If you have another alternative, you're welcome to post it and argue in
its favor, but don't start taking things I say out of context and trying to
twist them to mean something I obviously didn't intend.

"Porky" wrote in message
. ..

"Jim Carr" wrote in message
news:jJp9d.3557$_a3.1033@fed1read05...
"Porky" wrote in message
t...

It was Doppler's train experiment, not Einstein's.

You've obviously never read "Relativity - The Special and General
Theory"
by
some old guy named Albert Einstein. He only mentions the train and
embankment about a zillion times.

But since this thread is about Doppler shift in a speaker, Doppler's
train
experiment is the more relevant one, is it not?

The person to whom you were replying talked about the Lorentz Transformation
and referred to "relatavistic mumbo-jumbo" so he was certainly entitled to
refer to Einstein. Since you were a smart-ass to him, I was a smart-ass back
to you.

"Porky" wrote in message
...

Wavelength and frequency are directly related and in any medium where
the
velocity of propagation is constant, as with sound, if one changes, the
other has to change as well and the change will be directly proportional,
there are no exceptions.

Are you being bullheaded or do you really not understand? I've given you
mind experiments and mathematics to prove you wrong, and all you can do is
repeat your same assertation with no proof. You never admit you're wrong, do
you? Show me one post in the hundreds where people have disagreed with you
where you admit you're wrong.

One thing you're overlooking is that if the
receiver is moving, in order to make a valid observation about what he
observes, your measuring device has to be moving with him, so the apparent
wavelength

Here we go again. Go back to the stationary source. The first wave strikes
the receiver. The receiver moves towards the source then STOPS BEFORE THE
SECOND WAVE ARRIVES. According to you since the receiver is not moving I
don't have to worry about the measuring stick moving. At the moment the
second wave strikes the receiver I take my measurement between it and the
first wave.

What's that distance? If you said the same as at the source, you would be
correct.

What's the frequency? Obviously the frequency is greater than at the source
because the second wave traveled for less time/distance before striking the
receiver.

Thus it is proved again.

To make it even more confusing, if you are traveling at a different
velocity and direction relative to the source than is the receiver, you'll
observations will be totally different than his.

My formula will correctly determine the wavelength even if the source and
receiver are moving. Plug in the numbers and try it yourself.

Frequency is time dependent. It tells how often some event occurs such as
the wave passing by us. Wavelength is not time dependent. It's the distance
between identical points between waves. If the speed is constant, there is a
mathematical relationship - on that we agree.

If we introduce other movement into the picture, we had better account for
it. You can't pretend it didn't happen, can we. You have no problems
adjusting the frequency based on the movement (Doppler Shift), so you had
better adjust the wavelength based on the movement as well.

This is my last post on the topic, Porky. If you don't understand by now,
you never will.